This invention relates to an apparatus for heating a pipe and/or a sleeve on a pipe or pipe joint.
It is common practice to apply a sleeve to a coated pipeline joint. The usual method involves the cleaning of rust scale and dirt from the joint, the preheating of the joint, the application of adhesive and a heat shrinkable sleeve to the joint without creating air bubbles between the pipe and the sleeve, and the bonding of the adhesive to both the pipe and the sleeve with good adhesion. In the past, a propane torch or an electrical induction heating has been used to effect preheating and sleeve application. Both methods have major drawbacks - the propane torch may overheat or underheat the pipe during the preheat stage and may burn or underheat the shrink sleeve during the application stage. Thus, successful application of a sleeve using a torch is dependent upon the skill and care exercised by the persons installing the sleeve. Electrical induction heating requires expensive equipment and skilled operators.
A search of the patent literature fails to disclose a solution to the above defined problems. Canadian Patent No. 983,335, issued to F. W. Mayo et al on Feb. 10, 1976, and U.S. Pats. Nos. 2,296,387, issued to H. V. Inskeep et al on Sept. 22, 1942; 3,074,704, issued to B. Ronay on Jan. 22, 1963 and 3,202,406, issued to W. L. Tack on Aug. 24, 1965 disclose heaters having some features in common with the invention described herein. However, none of the patented devices could be used to effect uniform heating of the type proposed in the present case.
The object of this invention is to provide a solution to the problem of pipe and sleeve or cover heating in the form of a relatively simple apparatus for heating an elongated cylindrical object, and more specifically, a pipe or a cover for the pipe.